I need a third opinion, please

  Here we go again...... after nine years of the entire right side of my throat
  being numb from a wisdom tooth extraction and 18 months of complete numbness on
  the left side due to a root canal,  they are once again telling me "we
  don't know!"! Apparently, the neurologist my HMO referred me to is not
  interested in finding the cause of the permanent numbness.  I was
  referred to him after refusing dental surgery. My refusal was due to the
  fear caused by permanent numbness of my throat from the local anesthetics
  used for the procedures listed above.
  After banging my relex points with a rubber
  hammer and sticking a Q-Tip in my throat to check for gag reflexes, he has
  informed my oral surgeon to proceed with surgery! I am reluctant to proceed
  based on the results of these two simple tests! One of my main concerns
  is the fact that the entire inside of my mouth went numb for two+
  weeks recently after taking erythromycin. Could all of these things be
  related to a (two year treated) B12 deficiency? I am terrified to proceed
  with anything that requires local anesthetic above my neck, for fear that
  I will end up with yet another permanent numbness!  
  Friday, he sent me for
  folate tests.  He claims that the muscle twitches, etc. that I have
  experienced since taking the erythromycin are being caused by folic acid
  deficiency, not B12, as I experienced two+years ago. Please let me know
  if you have any ideas/opinions regarding all of the above. Can a folate
  deficiency cause neurological symptoms? I have been unable to locate
  this information anywhere. Also, can Carbocaine cause permanent numbness
  in an area not related to the injection spot? Thank you!
Dear Risa:
Sorry to hear about all of your problems.  Since you are taking Vitamin B12, you shouldn't have a folate deficiency, especially if you are eating grains etc.  The erythromycin should not cause a problem with your folate level. Since I have not fully examined you nor seen the results of all of your testing, it is impossible to comment on your diagnosis.  The injection of the anesthesia might cause numbness in another location if the nerves that were make numb travelled to that other spot.  I hope that things get better for you.  What you may need to do, is to see another dentist and have him/her comment on all the problems stemming from your oral surgeries.  
Sincerely,
CCF Neuro[P] MD